This invention relates to a disc brake assembly for use with a rotor and suitable for a vehicle, such as an automobile or a commercial vehicle. More specifically, this invention relates to improvements of a disc brake assembly having two types of brakes, i.e., a service disc brake and a parking disc brake.
FIGS. 12 and 13 disclose a disc brake assembly in accordance with the prior art. This type of disc brake assembly comprises two fixed-caliper service disc brakes 11 and a mechanical floating-caliper parking disc brake 12 between the two fixed-caliper service disc brakes 11. The parking disc brake 12 and the service disc brakes 11 are peripherally distributed along a disc rotor 10 with equal intervals.
Calipers 11a of the respective service disc brakes 11 are fixed by two installation bolts 14 on a mounting bracket 13 which is a stationary part of the vehicle. The parking disc brake 12 includes a carrier 12b that supports a parking brake caliper 12a that is fixed on the mounting bracket 13 by second installation bolts 15.
The service disc brakes 11 include a pair of frictional pads (not shown in the diagram) that are pressed to the side surfaces of the rotor 10 by a fluid pressure operation mechanism built into the service disc brakes 11, thereby causing braking effect. And the parking disc brake 12 includes a pair of friction pads 12c, 12d that are pressured to the side surface of the rotor 10 by the mechanical operation mechanism built in the parking disc brake 12, thereby causing brake effect.
The above-described disc brake has several disadvantages. For example, the parking disc brake 12 has the carrier 12b as a component. Thus, both the carrier 12b and the second installation bolts 15 that fix the carrier 12b on the mounting bracket 13 require higher material costs, working costs, and surface treatment costs.
Also, because the parking disc brake 12 needs to be larger in the circumferential direction of the rotor 10 for the carrier 12b, the size of the parking disc brake 12 is increased. Since the disc brake needs to be a bit larger, it has disadvantages in the weight and the manufacturing cost as well as the fuel consumption of the vehicle.
This invention is intended to improve the above-points. To that end, the invention provides a smaller device with a lower cost. In one embodiment, a disc brake assembly comprises two hydraulic type service disc brakes that press a disc rotor from opposite sides to cause a braking effect, and further including a mechanical floating-caliper type disc brake for a parking brake, wherein the mechanical floating-caliper type parking disc brake is provided between the two hydraulic type service disc brakes which are disposed in the circumferential direction of the disc rotor with a certain interval, and wherein component parts of the two hydraulic type service disc brakes are used as a torque-receiving part of the mechanical floating-caliper type parking disc brake. In an alternate embodiment, the hydraulic type service disc brake is a fixed-caliper type. In another embodiment, the torque-receiving part is a caliper.
In yet another embodiment, the hydraulic type service disc brake is a floating-caliper type. In another embodiment, the torque-receiving part is a carrier.
In still another embodiment, a disc brake further includes tightening parts that attach said mechanical floating-caliper type parking disc brake on a stationary part, the tightening parts also attaching said hydraulic type service disc brake on the stationary part. Finally, in another embodiment, the mechanical floating-caliper type parking disc brake includes a spring chamber type operating mechanism.